PURPOSE: To obtain a bearing unit in which the strength of a fixed ring is held and which can be made small and lightweight by a method wherein the inside diameter of a through hole made in the fixed ring is made small.

CONSTITUTION: A tone wheel 21 is fixed to the outer circumferential face in the intermediate part of a rotating ring 5, and a sensor 24 is fixed to the inner circumferential face in the intermediate part of a fixed ring 2. The sensor 24 comprises a socket 32 for signal pickup. A plug 42 is inserted from a through hole 36 made in a part of the fixed ring 2, the tip of the plug 42 is inserted into the socket 32, and a signal voltage which is induced in the part of a coil 27 is taken out.